Odom. A drag coefficient Kd based on the 155mm shell, HE, M101

11 Pages·1.295 MB·English

by  Charles T.

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RANDUM- REPORT NO. 1167
SEPTEMBER 1958
A DRAG COEFFICIENT, KD, BASED ON
THE 155MM SHELL, HE, M 4.
CHARLES T. ODOM
f ASITT IAA
1958
OFPARIMENT OF THE ARMY PROJECT NO. 380307003
ORDNANCE RESEARCH AND DEVELOPMENT PROJECT NO. T83-0430
BALLISTIC RESEARCH LABORATORIES
AD E RMI GAU R YLAND
ABERDEEN PROVING GROUND, MARYLAND
BALLISTIC RESEARCH LABORATORIES
MEMORANDUM REPORT NO. 1167
SEPTEMBER 1958
/
A DRAG COEFFICIENT, KD,
BASED ON THE 155MM SHELL, HE, MI01
Charles T. Odom
(
Requests for additional copies of this report will be made direct to ASTIA.
Department of the Army Project No. 5B0307003
Ordnance Research and Development Project No. TB3-0430
ABERDEEN PROVING GROUND, MARYLAND
BALLISTIC RESEARCH LABORATORIES
MEMORANDUM REPORT NO. 1167
CTOdom/wec
Aberdeen Proving Ground, Md.
September 1958
A DRAG COEFFICIENT, KDP
BASED ON THE 155MM SHELL, HE, Mi01
ABSTRACT
Firing tables for the 155mm howitzer are being revised to reflect the
latest changes in table format and in the process will incorporate the most
recent information on performance and drag characteristics of the M107
shell. Drag coefficients, KD, obtained from transonic range measurements
of the M101 shell, identical to the M107 shell except for its wider rotating
band, were fitted with a series of polynomials. The fitting expressions and
a tabulation of the drag coefficients at small intervals of Mach Number are
given in this report.
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INTRODUCTION
Firing Tables for the i 55mm Howitzer are being revised to reflect the
latest changes in the format of artillery firing tables. In the process of
revising existing firing tables the practice in BRL has been to incorporate
into the revision the latest and best information available on the shell. More
recently active efforts have !nen made to employ in the ballistic computa-
tions of any firing table the drag function of the particular shell in question.
There were available from transonic range firings, measurements of
the zero yaw drag coefficient of the 155mm Shell, HE, MI01. The M101
shell is the standard HE shell for the 155mm gun and except for its wider
rotating band, which has a small effect on the drag of the projectile, it is
otherwise identical to the M107 shell which is the standard HE shell for the
155mm howitzer.
The transonic range measurements were fitted with a series of polynomials
and used in ballistic reductions of Ml07 shell range firing data. The first
time through, the reduction results indicated that some adjustment of the
drag coefficients in the subsonic region of velocities was desirable if the
ideal goal of a constant ballistic coefficient was to be approached. After the
adjustment reductions were again performed, the variation of ballistic
coefficient with muzzle velocity was reduced to an acceptable level. The
ballistic coefficient was still not a constant but the variation was minimized.
Following are the fitting expressions for the M101 shell drag coefficient.
Adjacent expressions were required to give the same value of K and its first
D
derivative at the junctur,' points.
In the Interval KD is given by
0.o - M-± 0.90 0.0579080038
0. 90 M 0. 96 44.26302428-138.8317032M
3
+144.7922431M 2-50. 12112525M
0.96 M 1.02 414.3525910-1262.4596067M
+1280.9650680M 2-432. 7252631M 3
1.02 . M 1.22 -0.4212674799+1. 029831902M
-0.4 621 525076M 2
1.22- M -1.3 8.911875950-20.35167306M
+15. 77773047M2 -4.085776562M3
1.3 -M Z. 6 (0.9415 + 0.1327M) 2.1
M5
5
The form factors and ballistic coeff 4 ent-s -of the M107 shell with respect
to the above drag functions are as folO
Charge M. V. i, form factor c, ballistic coefficient
f/s
1 680 0.9853 2 589
2 770 0.9853 2 589
3 880 0; 9853 2.389
4 1020 1b.150 2.513
5 1220 l;D3lZ5-0.0000513820 2.47379+0. 000130800
6 1520 i P1e3 -0. 0000348440 2. 51153+0.00009Z16
7 1850 0. 9444: ~0l083060 i: §,6
The above Ois dt'e it3f 4 sfihdittd gihlii weighi oi 95 pounds, 0 is the angle of
dep-Aii tl riiiis and does not exceed 1155.6 mils. The relation between"
ballistic coefficient, c, and form factor, i, is given by the expression,
c =-..%, where rn is the weight of the shell in pounds and d is the diameter
id'-
of the shell in inches. The form factor, i, is defined as the ratio between
the actual K of the shell and the K of the reference drag function used in
D
the ballistic reductions.
Figure I is a drawing of the MI01 shell, Figure 2 is plot of the drag
coefficients which are also shown numerically in the table which follows.
CHARLES T. ODOM
6
4.49
.4 - .60 2.44
NOTE
"ALL DIMENSIONS ARE IN ALIBERS
FIG. i SHELL, 155MM, HE, MIOI WITH FUZE,PD, M51A5
ci
- - - - - - - - - - - - - -
All If
TABLE OF THE DRAG COEFFICIENT, K D&
BASED ON THE 15 5MM SHE LL, HE, M 10O1
DRAG COEFFICIENT
M KD M KD M KD M KD
2.600 .096913 2.200 .107722 1.800 .121373 1.400 .138143
Z.590 .097154 Z.190 .108026 1.790 .121756 1.390 .138590
2.580 .097397 2.180 .108331 1.780 .122141 1.380 .139038
2.570 .097641 2.170 .108639 1.770 .122528 1.370 .139486
2.560 097886 2...160 .108948 1.760 .1Z2917 1.360 .139934
2.550 ,098133 2.150 .109259 1.750 .123308 1.350 .140381
2.540 .098380 2.140 .10957Z 1.740 .1Z3701 1.340 .140829
2.530 .098630 2.130 .109887 1.730 .124096 1.330 .141276
2.520 .098881 2.120 .110203 1.720 .124493 1.320 .141723
2.510 .099133 2.110 .110522 1.710 .124893 1.310 .142169
2.500 .099386 2.100 .110842 1.700 .125294 1.300 .142614
2.490 .099642 2.090 .111165 1.690 .1Z5697 1.290 .143047
2.480 .099898 2.080 .111489 1.680 .126102 1.280 .143474
2.470 .100156 2.070 .111815 1.670 .126510 1.270 .143917
2.460 .100416 Z.060 .112143 1.660 .126919 1.260 .144403
2.450 .100677 2.050 .112473 1.650 .127330 1.250 .144956
2.440 1100940 2.040 .112805 1,640 .127743 1.240 .145600
2.430 .101204 2.030 .113139 1.630 .128158 1.230 .146360
2.420 .101469 2.020 .113474 1,620 .128575 1.220 .147260
2.410 .101736 2.010 .1]3812 1.610 .128994 1.210 .148192
2.400 .102005 2.000 .114152 1.600 .129414 1.200 .149031
2.390 .102275 1.990 .114494 1.590 .129837 1.199 .149110
2.380 .102547 1.980 .114837 1.580' .130261 1.198 .149188
2.370 1102821 1.970 .115183 1.570 .130687 1.197 .149265
2.360 .103096 1.960 .115531 1.560 .131114 1.196 .149341
2.350 103372 1.950 .115881 1.550 .131544 1.195 .149416
2.340 .103651 1.940 .11623Z 1.540 .131974 1.194 .149491
2.330 .103930 1.930 .116586 1.530 .132407 1.193 .149564
2,320 .104212 1.920 .116942 1.520 .132841 1.192 .149636
Z.310 .104495 1.910 .117300 1.510 .133276 1.191 .149708
Z,300 .104780 1.900 .117660 1.500 .133713 1.190 .149778
2.290 .105066 1.890 .118022 1.490 .134151 1.189 .149848
2.280 .105355 1.880 .118386 1.480 .134591 1.188 .149917
2 270 .105644 1.870 .118752 1.470 .135031 1.187 .149984
2.260 .105936 1.860 .119120 1.460 .135473 1.186 .15001
Z.250 .106229 1.850 .119491 1.450 .135916 1.185 .150117
2.240 .106524 1.840 .119863 1.440 .136360 1.184 .150182
2.230 .1068Z 1.830 .120238 1.430 .136804 1.183 .150246
2.220 .107120 1.820 .120614 1.420 .137250 1.12 .150309
2,210 .107420 1.810 .120993 1.410 .137696 1.181 ,150372
2.200 .107722 1.800 121373 1,400 .138143 1.180 .150433
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DRAG COEFFICIENT
M K M K M K M K
D D D
1.180 .150433 1.140 .152127 1.I0 .1,52343 1.060 .151080
1.179 .150493 1.139 .152151 1.099 .152330 1.059 .151029
1.178 .150553 1.138 .152173 1.098 .152315 1.058 . 150978
1.177 .150611 1.137 .152195 1.097 .152300 1.057 .150925
1.176 .150669 1.136 .152216 1.096 .152283 1.056 .150872
1.175 .150726 1.135 .152235 1.095 .152266 1.055 .150818
1.174 .150781 1.134 .152Z54 1.094 .152248 1.054 .150762
1.173 .150836 1.133 .152272 1.093 .152229 1.053 .150707
1.172 .150890 1.132 .152289 1.092 .152209 1.052 .150650
1.171 .150943 1.131 .152305 1.091 .152188 1.051 .150592
1.170 .150995 1.130 .152320 1.090 .152166 1.050 .150533
1.169 .151046 1.129 .152334 1.089 .152143 1.049 .150473
1.-68 .151097 1.128 .152347 1.088 .152119 1.048 .150412
1.167 .151146 1.127 .152360 1.087 .152095 1.047 .150351
1.166 .151194 1.126 .152371 1.086 .152069 1.046 .150288
1.165 .151242 1.125 .152382 1.085 .152043 1.045 .150225
1.164 .151288 1.124 .152391 1.084 .152015 1.044 .150160
1.163 .151334 1.123 .152400 1.083 .151987 1.043 .150095
1.162 .151379 1.122 .152408 1.082 .151958 1.042 .150029
1.161 .151422 1.121 .152414 1.081 .151927 1.041 .149962
1.160 .151465 1.120 .152420 1.080 .151896 1.040 .149894
1.159 .151507 1.119 .152425 1.079 .151864 1.039 .149825
1.158 .151548 1.118 .152429 1.078 .151831 1.038 .149755
1.157 .151588 1.117 .152432 1.077 .151797 1.037 .149684
1.156 .151627 1.116 .152434 1.076 .151763 1.036 .149612
1.155 .151665 1.115 .152436 1.075 .151727 1.035 .149539
1.154 .151703 1.114 .152436 1.074 .151690 1.034 .149466
1.153 .151739 1.113 .152435 1.073 .151653 1.033 .149391
1.152 .151774 1.112 .152434 1.072 .151614 1.032 .149316
1.151 .151809 1.111 .152431 1.071 .151575 1.031 .149239
1.150 .151843 1.110 .152428 1.070 .151534 1.030 .149162
1.149 .151875 1.109 .152424 1.069 .151493 1.029 .149084
1.148 .151907 1.108 .152418 1.068 .151451 1.028 .149004
1.147 .151938 1.107 .152412 1.067 .151408 1.027 .148924
1.146 .151968 1.106 .152405 1.066 .151364 1.026 .148843
1.145 .151997 1.105 .1.2397 1.065 .151319 1.025 .148761
1.144 .152025 1.104 .152388 1.064 .151273 1.024 .148678
1.143 .152052 1.103 .152378 1.063 .151226 1.023 .148595
1.142 .152078 1.102 .152367 1.062 .151178 1.022 .148510
1.141 .152103 1.101 .152356 1.061 .151129 1.021 .148424
1.140 .152127 1.100 .152343 1.060 .151080 1.020 .148338
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